1. Field of the Invention
This present invention relates generally to the energy sector of gas and petroleum exploration and production, particularly to subsurface wellbore equipment and more particularly to an apparatus for the milling and cutting of tubulars (e.g., casing) with a tool body that is rotatable with a drill or work string as it centers and stabilizes itself within the wellbore.
2. General Background of the Invention
Oilfield wellbores can be made up and maintained through a series of tubulars (e.g., casings). These casings normally extend to the bottom of the wellbore in several positions or in multiples, wherein the larger casing encapsulates a smaller casing. In some instances, there can be two or three casings, each encapsulated by a larger casing. These multiple casings can be eccentric to each other. These casings can have concrete or cement pumped between them to prevent bottom hole pressure from penetrating to the surface. The maintaining and management of these casings are of vital importance throughout the life of the well.
The integrity of the casing can be breached by collapse or corrosion. In such a case, they must be repaired. The collapsed or corroded section must be removed. Appropriate repairs are then performed. It is this procedure of removing existing damaged casing that this present invention entails.
This is a blind operation in the sense of not being able to see the procedure as it is happening. Other indicators must be used to do this operation properly. Weight indicators and pump pressures along with the knowledge to read these types of measurements are needed.
The operation and centralization of the tool apparatus of the present invention is conducted down hole wherein rotation of the tool body rotates one or more blades that cut the casing. In some instances only one casing is removed, which could be the innermost, smallest casing. When the device is sent to mill out the innermost casing, it should not cut and mill beyond the dimensions of the innermost casing. Damage to the integrity of the larger casing that is encapsulating this smaller casing should be avoided.
In some wellbore situations, the second innermost casing is milled, typically after the first innermost casing has been milled. A tool must have the ability to be setup to perform the same procedure as it did in the innermost casing but still maintain the ability to traverse through the inner diameter of the innermost casing.
Centralization of the tool body is perfected in most situations involving operations in casing. Centralization of the tool body can be more difficult if having to pass through a smaller internal diameter casing or some other form of restriction. The length of centralization to stabilize and centralize a tool is beneficial, in the milling or cutting operation.
The following U.S. Patents and U.S. Patent Application Publications are incorporated herein by reference (as are all references to which they refer): U.S. Pat. Nos. 2,899,000; 5,732,770; 9,187,971; 2013/0292108.